基于Geomagic对多个扫描数据精确注册过程的实现

利用逆向工程软件Geomagic Studio对多个扫描数据进行精确拼接,通过点云的过滤、手动注册、全局注册一系列过程,阐述了对于多个扫描数据精确注册过程的实现。     

局部分体式装配工艺在491QE汽车发动机凸轮轴上的应用

针对491QE汽车发动机整体式凸轮轴更改为由凸轮轴、齿轮、支承轴颈和隔套共4种零件装配而成的局部分体式凸轮轴的相关问题,通过更改齿轮的材料、提高齿轮加工精度等技术措施,降低了齿轮报废率,提升了凸轮轴制造合格率。     

考虑壁面粗糙度的双流体颗粒-壁面碰撞模型

提出了考虑壁面粗糙度的双流体颗粒－壁面碰撞模型，将轨道模型中颗粒碰壁模型考虑壁面粗糙度和双流体模型中用概率密度函数积分法处理颗粒与光滑壁面碰撞模型的优点结合起来，引入壁面粗糙度对碰壁颗粒湍流影响的机理。数值模拟结果表明，由于考虑了各方面雷诺应力之间的相互转化，雷诺应力从平均运动中得到能量，以及壁面对运动的衰减作用等因素，包括摩擦系数、恢复系统、壁面粗糙度等物理参数的颗粒－壁面碰撞模型作为边界条件时，得到的结果与实验符合得更好。     

Dynamic response of prismatic metallic sandwich tubes under combined internal shock pressure and thermal load

This paper presents an analytical model for the transient thermomechanical response in the sandwich tube subjected to internal shock pressure and thermal load. A sandwich model (3-layers model) and a multilayer model for predicting transient temperature are proposed, and the effective thermal conductivities in each layer are obtained by the analytical method based on the Fourier law of conduction. The analysis of dynamic response is conducted by using the high order sandwich shell models, considering the shear deformation and compressibility of the core. Moreover, several numerical simulations are carried out by finite element (FE) analysis, which are compared with the results obtained by using analytical models. The slight discrepancies between the numerical simulations and analytical results indicate that the sandwich model (3-layers model) can predict the transient temperature in the sandwich tube correctly, and the thermomechanical response obtained by the high order sandwich shell model is within acceptable accuracy. Thermal stresses are strongly dependent on temperature gradient in the sandwich wall. The dynamic resultant forces with large amplitudes will induce structural fatigue, which is harmful to the structural life and reliability. Therefore, the thermal stresses should be considered for the design of sandwich tubes or pipes subjected to thermomechanical load.     

Transient dynamic analysis of higher order sandwich and composite arches

A higher order refined model with isoparametric elements is proposed to study the transient dynamic response of laminated arches/curved beams. The strain field is modeled through cubic axial, cubic transverse shear and linear transverse normal strain components. As the cross-sectional warping is accurately modeled by this theory, the shear correction factor is rendered redundant. The stress–strain relationship is derived from an orthotropic lamina in a three-dimensional state of stress, so that angle-ply laminates can be studied through one-dimensional elements. Consistent mass matrix is constituted for the equation of motion, which is solved by Newmark integration scheme. The higher order formulation is validated with available results and subsequently applied to arches with various curvatures, aspect ratios, boundary conditions, loadings and lamination schemes to evaluate its transient dynamic performance and suitable conclusions are drawn.     

Stochastic post buckling analysis of laminated composite cylindrical shell panel subjected to hygrothermomechanical loading

In this paper, the effect of random system properties on the post buckling load of geometrically nonlinear laminated composite cylindrical shell panel subjected to hygrothermomechanical loading is investigated. System parameters are assumed as independent random variables. The higher order shear deformation theory and von-Karman nonlinear kinematics are used for basic formulation. The elastic and hygrothermal properties of the composite material are considered to be dependent on temperature and moisture concentration using micromechanical approach. A direct iterative based C⁰ nonlinear finite element method in conjunction with first-order perturbation technique proposed by present author for the plate is extended for shell panel subjected to hygrothermomechanical loading to compute the second-order statistics (mean and variances) of laminated composite cylindrical shell panel. The effect of random system properties, plate geometry, stacking sequences, support conditions, fiber volume fractions and temperature and moisture distributions on hygrothermomechanical post-buckling load of the laminated cylindrical shell panel are presented. The performance of outlined stochastic approach has been validated by comparing the present results with those available in the literature and independent Monte Carlo simulation.     

Dynamic investigation of laminated composite beams with shear and rotary inertia effect subjected to the moving oscillators using FEM

An algorithm based on the finite element method (FEM) has been developed to study the dynamic response of composite laminated beams subjected to the moving oscillator. The first order shear deformation theory (FSDT) is assumed for the beam model. The algorithm accounts for the complete dynamic interaction between the components of system. The proposed method can also be applied to the general moving mass and the simplified moving force problems. After deriving the governing equations of motion of beam and oscillator, the corresponding equations of motion are integrated by applying the Newmark’s time integration procedures to obtain the system responses in each time step. The numerical results of free vibration and moving force problems analysis of isotropic and composite laminated beams are presented and, whenever possible, compared to the available analytical solution and other numerical results in order to demonstrate the accuracy of the present method. In addition, parametric analysis is carried out over a wide range of velocities and mass, frequency and damping ratios of system components.     

历史保护建筑改建工程中多联空调系统的运用

分析了暖通设计中如何找到历史保护建筑改建工程“修旧如旧”[1]与“满足建筑使用功能及保证人员舒适度”的最佳平衡点,并结合实际工程介绍了多联空调系统在历史保护建筑中的运用.从“空调系统冷热源的选择”与“空调末端系统的选择”两方面对此进行深入分析,说明了多联空调系统在历史保护建筑改建过程中的优势.